Airplane propeller



Fehzs, 1932. n, G'H F T 4 1,846,216

AIRPLANE PROPELLER Filed Aug. 1. 1930 INVENTOR c Z Lirlztfool BY @qimATTORNEY Patented Feb. 23, 1932 JAMES T. LIGHTFOOT, F MERCEI),CALIFORNIA AIRPLANE rnornrmna Application filed August 1, 1930. SerialNo.4'72,250.

This invention relates to airplanes, and particularly to the propulsivemeans thereof. The principal objects of my invention are to provide apropeller of such form that it has a better hold on the air than theordinary type; one with which a higher speed of the plane with a lowerengine speed and propeller speed may be attained, so that vibration andnoise are minimized; and a propeller arrangement which is so mounted onthe airplane that the plane Will have a very steady gliding movementthrough the air.

A further object of the invention is to produce a simple and inexpensivedevice and yet one which will be exceedingly effective for the purposefor which it is designed.

These objects I acomplish by means of such structure and relativearrangement of parts as will fully appear by a perusal of the followingspecification and claims.

In the drawings similar characters of reference indicate correspondingparts in the several views:

l ig. 1 is a top plan view of an airplane of the monoplane type, asequipped with my propeller arrangement.

Fig. :2 is a longitudinal edge view of a propeller.

Fig. 8 is a cross section of the propeller on the line of Fig. 2.

Referring now more particularly to the characters of reference on thedrawings, the

airplane as shown may be one of a standard type comprising essentially afuselage 1 having a wing 2 projecting laterally from the same adjacentits forward end, and substantially on the same level as the fuselage, asis the common practice in monoplane construction. My improved propellerarrangement which is mounted in connection with such airplane consistses entially of two propeller units, which are disposed rearwardly of thei win to the sides of the fuselage.

Each such unit comprises a shaft 3 extending lengthwise of the airplaneand laterally spaced relative to the fusela 'e. This shaft is journaledin end bearings 4, the forward one of which is mounted in connectionwith the back edge of the wing, while the rear one is mounted on a lateally extending spar 5 secured to the fuselage. Fixed on the shaft atsuitable longitudinally spaced pointsfirn termediate the bearings arespider units,each

comprising rigid radiallyextending and op posed arms 6 to the outer endsof which the '35 blades or vanes 7 of the propeller are fixed.

These blades are of substantially rectangular form and are of suchlength as to extend nearly the full distance between the wing and a thespar. The blades however are somewhat 0 wider at the rear than at thefront, and since their inner edges are preferably parallel to each otherand to the shaft, the outer edges of said blades diverge from each othertoward 1 the rear endand relative to the plane of the shaft. The bladesmay be made of sheetmetal or the like of substantially even thicknessthroughout and arebent or otherwise formed with a considerable,curvature as at 8 which extends for their full length toward their outeredges. This curvature is concave relative to the direction of rotationof the propeller, as indicated in Fig. 3. The spider or arm units aredisposed in different racli'alrea lation to each other on the shaft 30that the blades, which are actually straight from end to end will bedisposed at a certain pitch relative to the axial plane of the shaft asshown in Fig. 2.

The shafts of the two propeller units are 30 adapted to be rotated atthe same speed and in opposite directions, or so that the blades whenuppermostturn away from each other, by any suitable means. In thepresent in stance such means is shown as being atransverse shaft 9mounted on the wing and connected to the adjacent ends of the shafts? bybevel gearing 10. The shaft 9 in turn is geared as at 11 to a gas engine12 or other power plant mounted in the fuselage.

By means of this construction and due to the direction of rotation ofthe propellers relative to the concavity ofthe blades, the air isengaged forthe full length thereof.

Since the blades are disposed at an angle or pitch to'their shafts andto the line of travel of the airplanepthey have an auger-like action inthe air, forcing the air rearwardly with a subsequent forward propulsionof the airplane. Since the width of the blades, or

' 50 by Letters Patent is:

.rre ll r- 1 the diameter of the propellers as a whole is somewhatgreater at the rear than at their forward ends, the air as thrownrearwardly ward portions of the blades, will not clear the rear portionsof the blades as quickly as would otherwise be the case. Some of thiscentrifugally thrown air therefore remains engaged with or is reengaged'by the blades toward their rear ends, which aids in the propulsiveeffort of the propellers.

As a result of the particular form of the propeller and of the relationof the propellers to each other and to the fuselage, an ordinary glidingmovement is imparted to the airplane and the craft may travel at ahighspeed, With a relatively slow speed of rotation of the propellers andengine, and with a consequent minimum of vibration. Such movement of theairplane is thus had partly on account of the counterbalancing effect ofthe opposed V propellers, and partly because of the relatively greatvolumes of the air constantly engaged by such propellers. The propellersbethe fuselage, the sides of the latter catch air thrown centrifugallyfrom the adjacent blades of the propellers, and such air tends to holdthe airplane steady on account of the opposed and balancing pressurewhich it exert against the fuselage.

, Though'I have here shown and described the propellers as only having apair of opposed blades, it is of course to be understood that the numberof blades may be increased if desired without affecting the principle ofoperation of the structure. From the foregoing description it will bereadily seenthat I have produced such a device as substantially fulfillsthe objects 0 the invention as set forth herein.

and centrifugally by the action of the for ing in substantial horizontalalinement with 3. A propeller as in claim 2, in which the outer edges ofthe blades diverge at a slight angle relative to each other from fronttorear whereby the propeller is of greater diameter at the rear than atthe front.

4. A propeller comprising a shaft, and opposed straight edged bladesextending lengthwise of the shaft, the blades being straight from end toend in their longitudinal planes and set at an acute angle to the axial76 plane of the shaft, and having also a transverse twist whereby theirouter and inner longitudinal edges are disposed at different angles tothe axial plane of the shaft.

In testimony whereof I afiix my signature. 80

JAMES T. LIGHTFOOT.

7 While this specification sets forth in detail the present andpreferred construction of the device, still in practice suchdeviationsfrom such detail may be resorted to as do not form a departurefrom the spirit of the invention, as defined by the appended claims.

' Having thus described my invention what I claim as new and useful anddesire to secure 1. Apropeller comprising opposed blades extendinglengthwise of the shaft and mounted in connection therewith insubstantially radial relation thereto; said blades from end to endbeingdisposed at a constant angle to the, axial plane of the shaft.

. stantially parallel relation to each other but set at an angle to theaxial plane of the shaft;

a shaft, and i the outer portions of the blades being formed for theirfull length with a concave curvature relative to the direction ofrotation of the

